Joseph L. Casale wrote:
The secondary disc was used in a lab rig to boot off of and test something after which the primary was replaced and the system was booted off of. It saw the secondary as more recent and dropped the primary so, the secondary was removed and the primary was used to boot.
Figuring that made it more recent, even after it was restarted with the "now older" secondary, it still wants to drop the primary?
W/o blowing out the secondary (it can't be hot added) how can I force the primary to not be dropped? I'm amused that even with it used to boot solo, and hence timestamps validating it as most recent, md will only use the secondary to start from?
Unless there is something on the primary that you need to keep, just re-sync from the active partition and next time they will come up paired: mdadm --add md_device missing_partition cat /proc/mdstat to see the status
If you need to keep something on the primary, remove the secondary and reboot several times. I think there is a count of clean shutdowns that is used to determine if one is more current than the other - maybe there is a more intelligent way to update it, though. Then when you get the right one active, sync to the other.